A PART of the matter presented in this volume was published several years ago by the Wisconsin Biological Survey, under the title “Instincts and Habits of the Solitary Wasps.” These chapters have been revised and modified, and new matter based upon later work has been added, in the hope that in their present less technical form the observations recorded will be of interest to the general reader.

For a number of the text cuts used in this volume we are indebted to the courtesy of Dr. E. A. Birge, Director of the Wisconsin Geological and Natural History Survey.